LP Announces Expanded Scope of UL-Listed 2-Hour Wall Assemblies with LP® FlameBlock® Fire-Rated Oriented Strand Board Sheathing

LP Building Products announced an expanded scope of UL listings, including a new insulation option in the UL-listed BXUV.U349 wall assembly with LP^® FlameBlock^® Fire-Rated Oriented Strand Board Sheathing. Following a full-scale, ASTM E119 (UL 263) test, the alternate assembly, using R-13 fiberglass insulation instead of mineral wool insulation, passed a 2-hour interior burn requirement, earning UL approval. In addition, a one-hour exterior burn rating was earned for a similar assembly with mineral wool insulation and exterior cladding, as described in a new UL listing, BXUV.W408.

"There were two main objectives tied to this testing,” said Judy Musgrove, OSB marketing manager. "First our goal was to reduce the cost of the U349 2-hour wall assembly by creating an option for using fiberglass insulation. Second, we wanted to offer an exterior wall assembly suitable for Type III buildings that is rated from both sides. By achieving these objectives, we’ve created more options for architects, engineers, and builders who design and construct these buildings, which are typically taller than four stories.”

The fiberglass insulation option in the updated U349 listing reduces the cost of load-bearing walls rated for burning from the inside only, while the new W408 assembly provides a more efficient method of meeting code requirements in walls located close to property lines or adjacent buildings, where exterior fire ratings also come into play. These wall assemblies also help property owners better utilize valuable urban land by reducing the cost of adding valuable space to mixed-use and multi-family structures.”

The International Building Code allows for a height of up to five stories of wood construction for a residential building with two-hour rated exterior walls. Typically two-hour rated exterior walls use one or two layers of exterior gypsum sheathing on the exterior side of the framing, often in combination with a layer of wood structural panels. The U349 and W408 assemblies, however, utilize LP FlameBlock Sheathing as the exterior wall sheathing to meet both structural and fire requirements.

Not only does this approach save the expense of purchasing exterior, fire-rated gypsum board, it results in significant a labor savings. In addition, use of LP FlameBlock in these exterior walls reduces dead load and can potentially improve design flexibility due to the sheathing’s superior shear capacity.

The new W408 listing includes options for a range of exterior claddings, including OSB-based siding, plywood, and fiber cement claddings, as well as other materials known to have equal or greater fire resistance. The excellent fastener-holding ability of LP FlameBlock can simplify installation of exterior facing materials, potentially providing additional labor and time savings.

LP FlameBlock, as part of the U349 wall, has been used in Type III projects across the country, including buildings in College Park, MD, Nashville, TN, Issaquah, WA, and Merrifield, VA.

LP FlameBlock offers structural strength and fire resistance in one panel. Created by applying a proprietary, non-combustible, fiberglass-reinforced Pyrotite^® coating to LP OSB panels, LP FlameBlock is an ICC certified (ESR-1365), PS2-rated structural sheathing with a Class A Flame Spread Rating. The product is also Exposure-1 rated, provides extended burn-through resistance, delivers a 20-minute thermal barrier (ASTM E119), and contains no hazardous chemicals.

LP FlameBlock can reduce the time and cost associated with having to install either double-layers of gypsum or a combination of gypsum and structural sheathing. The product is available in a variety of PS2-rated thicknesses and lengths, including Struc-1, and is paintable. LP FlameBlock panels are installed with the same tools and fasteners used for installation of other structural sheathing panels.

About LP Building Products

Louisiana-Pacific Corporation is a leading manufacturer of quality engineered wood building materials including OSB, structural framing products, and exterior siding for use in residential, industrial and light commercial construction. From manufacturing facilities in the U.S., Canada, Chile and Brazil, LP products are sold to builders and homeowners through building materials distributors and dealers and retail home centers. Founded in 1973, LP is headquartered in Nashville, Tennessee, and traded on the New York Stock Exchange under LPX. For more information, visit www.lpcorp.com.